Rhythm/livestore: Use liveTraces for max trace size

[joe-elliott]

What this PR does:
Correctly uses traceSizes instead of liveTraces for tracking trace sizes across multiple flushes of live traces.

Other changes

• Tests updated to directly confirm expected behavior
• Swapped max trace idle/max trace size b/c they were in the wrong places
• Added a rate limited logger for trace too large so we can diagnose tenant issues

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[mattdurham]

lets goooo!